The present disclosure is directed to an apparatus for removing a sample from a liquid storage container such as a hold below the deck of a tanker or the top or cover of a fixed tank for receiving and storing thousands of gallons of a liquid product. Also, it can be moved from one tank to the next, both ship board or at fixed tanks in a tank yard or the like. Examples will be used below including barges, tanks and ships. The liquid products are typically subject to vaporization. Indeed, they may be formed of many constituent components so that there is a tendency of the liquid in the storage container to vaporize when exposed to the atmosphere. The several constituents may have different vapor pressures. Some may vaporize quite readily and others may vaporize rather slowly, or perhaps not at all. As a generalization, these products are described as petrochemical products. They are normally valuable products but they are not freely vented to the atmosphere for vaporization. Moreover, such products have to be sampled, tested, measured and assayed. It is not uncommon for the tank of a large vessel to be quite deep, perhaps as much as 100 feet in depth, or about 30 meters. It is not uncommon for the storage compartment of a tanker to be 10 meters in length. The petrochemical cargo which is placed in such a large tank or container can be very large and can fill the storage container almost to the top of the container. In these situations, it is necessary to make periodic measurements to test or check the cargo in the tanker to assure that a product is delivered which has a known purity. The device of this disclosure is a measuring apparatus which can be used to take a sample from a closed tank aboard a vessel. More importantly, it is a device which can take a sample from a controlled depth in a tank. Consider the example of an ocean going vessel which has a large storage tank of 30 meters in depth normally used to haul petrochemical products. As a generalization, the bottom of the tank will collect a layer of sediment and typically also a thin layer of water will collect on top of the sediment. The sediment will settle to the bottom of the tank by virtue of the relative difference in the weight of the materials. The water will settle to the bottom of the tank also because it is normally heavier than most petrochemical products. Most of the time, the petrochemical product placed in the tank will float on the water. More than that, it may stratify by separating into constituent components. For instance if a cargo is shipped on a transatlantic passage, it may stay in the tank of the vessel for perhaps 10 to 20 days depending on the delays encountered in loading and off loading. During that interval and dependent on the agitation of the tank, the cargo may stratify into two or three different layers. On arrival at a port after such a transatlantic voyage, it may be necessary to remove samples from the tank. It is extremely important to remove samples from a controlled depth. The depth normally is known because it is intimately connected with the vessel size and is the type of data which is always available.
The present apparatus is directed to a sample removal system which can be connected with a tank to remove a calibrated sample volume from a specified depth. For instance, if a sample of the sediment and water at the bottom of the tank is desired, the device of the present disclosure includes a sample container which is lowered into the tank to the bottom. Normally, the clearance between the top of the tank and the bottom of the tank is well known in advance. If it is suspected that the petrochemical cargo has stratified into several layers, different samples can be taken from different depths. In each instance, a small container is lowered to a desired depth and then is retrieved on a measuring tape or line. The measuring tape is calibrated so that the depth of the measuring instrument and container is known. Moreover, this procedure enables the testing of the materials by retrieval from the tank and subsequent transmission to a laboratory.
It is not enough merely to retrieve a sample container of liquid from a tank. While the container is small for instance, one liter or less, there is always the difficulty of getting the liquid out of the container and into another container for easy transportation to a remote facility for testing. More than that, there is always the possibility that the retrieved liquid cargo may well further be changed by loss of light vapor constituents. These typically are the lighter molecules which have substantial value in the product, and which vaporize too readily. This can include dangerous constituents such as benzene which is regulated severely for its escape into the atmosphere. This also can include the lighter constituents of the common constituents, namely, gasoline such as the C.sub.4, C.sub.5, C.sub.6, etc. components. The present apparatus is a system which enables test personnel to retrieve a liquid sample from a tank without releasing fumes to the atmosphere, and without spilling liquid. It is a system which permits the sample measuring container to be lowered down into the tank and into the liquid cargo for retrieval of a sample or specimen from a determined depth. Moreover, the entire process of lowering the container into the liquid cargo and making retrieval is accomplished in a closed vessel so that there are no fumes permitted to escape to the atmosphere. An important feature of the present apparatus is the ability of the equipment to readily remove a measured sample and to subsequently transfer the sample from the equipment into a septum closed bottle which can then be transported easily and readily to a test facility without escape of fumes, and also without risk of spilling the contents of the bottle. Furthermore, the system includes a means and a mechanism whereby the sample which is retrieved can be delivered into a sized measuring bottle for easy transportation to a test laboratory and the like. Indeed, the present apparatus is a system which, when considering the taking of samples from a tank which is 30 meters in depth, can readily obtain 6 or 8 samples in separate bottles, each sealed against leakage, and each prepared for immediate transportation to a laboratory. All of this can be obtained at a single site on the top of the decking or structure which defines the deep tank, and all of this can be accomplished readily with minimal vapor escape to the atmosphere.
The present apparatus is summarized as a permanently installed ball valve including a quarter turn rotating trunnion and shaft which positions the valve so that a vertical passage through the valve into the tank is defined. It is typically mounted on the deck over a tank. The ball valve is closed ordinarily, but, on quarter turn rotation, the ball is moved to an aligned position so that a vertical passage through the ball valve is opened. The ball valve connects with an open ended upper port. By means of a suitable fitting, an upstanding sampler column is positioned over that. It is elongate and hollow, defining a double wall. It is sufficiently tall that it receives and holds a sample container. This sample container is weighted at the bottom so it hangs upright. At the top end, it has a hook or eyelet which enables it to be connected with an elongate measuring tape. The sample container is lowered downwardly through the open ball valve and into the tank. The sample container is constructed to receive and hold a sized sample. Moreover, the upstanding hollow column which defines the equipment includes an over head storage reel or drum which holds the several bights of an elongate steel measuring tape. It is calibrated to an adequate length to assure that the sample container is lowered to any depth in the tank. The upper end of the upstanding sampler test equipment is equipped with a fitting which enables introduction of nitrogen under pressure. The air or nitrogen under pressure is forced downwardly into the apparatus and provides a fluid drive for urging the liquid from the storage container. Sample is forced downwardly and flows into an annular space defined by a double wall construction. Sample must flow upwardly through the double wall space to the top end of the annular space between the double walled construction. The liquid is driven out through a fitting. It then flows into a control valve. This valve is operative to provide fluid flow downwardly through the first needle of a pair of needles which are inserted through a septum covering over the mouth of a small sample bottle. The bottle is filled by flow through this route but there is also an outlet passage from the bottle through a second needle. When overflowing or expelling air, this flows through a controlled pathway into a disposable filter in a container which is filled with charcoal or some other particulate carbon product for filtration. In turn, any discharge then flows into an outlet conduit. The fluid flow is under power of either nitrogen introduced to push the liquid out of the system, or, in the alternative, fluid flow is initiated by provision of a vacuum pump at the outlet end (pulling the vapors through a carbon filter). The present apparatus thus enables a sample to be retrieved from a large tank holding great quantities of a petrochemical product and delivery of a specified size of sample into a sample container, and all of this is accomplished substantially without permitting fumes to escape to atmosphere.